Handling of fasteners within a surgical instrument

ABSTRACT

Surgical instruments and their methods of use are disclosed. In some embodiments, the surgical instrument may include a handle and an elongated shaft assembly extending distally from the handle. The surgical instrument may also include a fastener deployment system for deploying fasteners from the elongated shaft assembly including a reciprocating driveshaft disposed within the elongated shaft assembly. The driveshaft may include an internal channel and at least one guide surface shaped and arranged to maintain an orientation of at least one fastener in the channel of the driveshaft. In other embodiments, the fastener deployment system may include a follower disposed within the elongated shaft assembly for displacing one or more fasteners within the elongated shaft assembly towards a distal fastener deployment position.

FIELD

Disclosed embodiments are related to the handling of fasteners within asurgical instrument.

BACKGROUND

A surgical mesh fabric or other prosthetic repair fabric may be used tosurgically repair a hernia. The prosthetic repair fabric is typicallyplaced in an open procedure or laparoscopically. To secure the repairfabric in place, one or more fasteners may be deployed through theprosthetic repair fabric and into the underlying tissue. Oftentimes,surgical instruments used during the surgical repair of a hernia, orother appropriate procedure, include magazines, or other structures,that are capable of holding a plurality of fasteners for deployment fromthe surgical instrument. The inclusion of a plurality of fastenerswithin the surgical instrument may increase the speed of the procedureand may also reduce the need to remove and re-introduce the surgicalinstrument into a surgical field to provide additional fasteners.

SUMMARY

In one embodiment, a surgical instrument includes a handle and anelongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system includinga driveshaft disposed within the elongated shaft assembly. Thedriveshaft includes at least one guide surface that at least partiallydefines an internal channel of the driveshaft. The at least one guidesurface is shaped and arranged to maintain an orientation of at leastone fastener in the channel of the driveshaft.

In another embodiment, a method for operating a surgical instrumentincludes: providing a surgical instrument including: a handle; anelongated shaft assembly extending distally from the handle; a fastenerdeployment system for deploying fasteners from the elongated shaftassembly including a driveshaft disposed within the elongated shaftassembly, wherein the driveshaft includes an internal channel; and atleast one fastener disposed within the internal channel of thedriveshaft; actuating the fastener deployment system to displace thedriveshaft and deploy a second fastener from the elongated shaftassembly; and maintaining an orientation of the at least one fastenerrelative to the driveshaft during actuation of the fastener deploymentsystem to deploy the second fastener.

In yet another embodiment, a surgical instrument includes a handle andan elongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system fordeploying fasteners from the elongated shaft assembly including adriveshaft disposed within the elongated shaft assembly. The driveshaftincludes an internal channel adapted and arranged to contain at leastone fastener. A cross-section of the channel within a distally locatedportion of the driveshaft also includes a flat portion and a roundportion.

In another embodiment, a surgical instrument includes a handle and anelongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system fordeploying fasteners from the elongated shaft assembly and a followerdisposed within the elongated shaft assembly and associated with one ormore fasteners disposed within the elongated shaft assembly. Actuationof the fastener deployment system compresses the follower from a firstlength to a second length to apply a distally directed force to the oneor more fasteners and displace the fasteners in a distal direction.During displacement of the one or more fasteners the follower expandfrom the second length to the first length.

In yet another embodiment, a surgical instrument includes a handle anelongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system fordeploying fasteners from the elongated shaft assembly. The fastenerdeployment system includes a driveshaft disposed within the elongatedshaft assembly and a follower disposed within the elongated shaftassembly and associated with the driveshaft. Distal displacement of thedriveshaft deploys a fastener from the elongated shaft assembly anddisplaces the follower in a distal direction to displace one or morefasteners disposed in the elongated shaft assembly in a distaldirection. A force applied to the deployed fastener by the driveshaft isgreater than a force applied to the one or more fasteners by thefollower.

In another embodiment, a surgical instrument includes a handle and anelongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system fordeploying fasteners from the elongated shaft assembly and a followerdisposed within the elongated shaft assembly for displacing one or morefasteners within the elongated shaft assembly in a distal direction. Thefollower applies a first force to the one or more fasteners prior toactuation of the fastener deployment system and a second force to theone or more fasteners after actuation of the fastener deployment systemis begun to displace the one or more fasteners in the distal direction.The elongated shaft assembly is configured to apply a first restrainingforce and a second restraining force to the one or more fasteners. Thefirst force is less than the first restraining force. Further, thesecond force is greater than the first restraining force and less thanthe second restraining force.

In yet another embodiment, a surgical instrument includes a handle andan elongated shaft assembly extending distally from the handle. A firstrestraining element and a second restraining element are associated withthe elongated shaft assembly. The second restraining element is locateddistally from the first restraining element. The first restrainingelement and the second restraining element define a fastener deploymentposition. The surgical instrument also includes a fastener deploymentsystem for deploying fasteners from the elongated shaft assembly. Thefastener deployment system includes a driveshaft adapted and arranged toapply a deployment force to a fastener located in the fastenerdeployment position.

In another embodiment, a method of operating a surgical instrumentincludes: providing: a handle; an elongated shaft assembly extendingdistally from the handle; a fastener deployment system for deployingfasteners from the elongated shaft assembly; and a follower disposedwithin the elongated shaft assembly and associated with one or morefasteners disposed within the elongated shaft assembly; actuating thefastener deployment system to deploy a fastener from the elongated shaftassembly; distally displacing the follower to compress the follower froma first length to a second length to apply a distally directed force toone or more fasteners to displace the one or more fasteners in a distaldirection, and wherein during displacement of the one or more fastenersthe follower expands from the second length to the first length.

In yet another embodiment, a surgical instrument includes a handle andan elongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system fordeploying fasteners from the elongated shaft assembly. The fastenerdeployment system includes a driveshaft. A follower is configured todisplace a stack of fasteners and is disposed within the driveshaft. Thefollower and driveshaft form a walking beam assembly to sequentiallydisplace the follower in a distal direction during each actuation cycleof the fastener deployment system.

In another embodiment, a surgical instrument includes a handle and anelongated shaft assembly extending distally from the handle. Thesurgical instrument also includes a fastener deployment system fordeploying fasteners from the elongated shaft assembly. The fastenerdeployment system includes a driveshaft. An anti-backup element isassociated with the driveshaft such that actuation of the fastenerdeployment system distally displaces the driveshaft and distal movementof the driveshaft extends the anti-backup element by a preselectedlength during each actuation cycle.

It should be appreciated that the foregoing concepts, and additionalconcepts discussed below, may be arranged in any suitable combination,as the present disclosure is not limited in this respect. The foregoingand other aspects, embodiments, and features of the present teachingscan be more fully understood from the following description inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures may be represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a schematic representation of an articulable surgicalinstrument;

FIG. 2 is a schematic representation of the interior of the surgicalinstrument handle of FIG. 1;

FIG. 3 is a schematic exploded view of the elongated shaft assembly andthe components disposed within the channel of the elongated shaftassembly;

FIG. 4 is a schematic representation of a follower;

FIG. 5 is a schematic representation of a distal portion of thereciprocating driveshaft;

FIG. 6 is a schematic cross-sectional view of the follower locatedwithin the driveshaft;

FIG. 7A is a schematic representation of a stack of fasteners and thefollower in an unbiased position;

FIG. 7B is a schematic representation of the stack of fasteners and thefollower of FIG. 6 with a biasing force applied;

FIG. 7C is a schematic representation of the stack of fasteners and thefollower of FIG. 6 after the stack of fasteners have been distallydisplaced;

FIG. 8A is a schematic representation of a distal portion of theanti-backup mechanism;

FIG. 8B is a schematic representation of the anti-backup mechanismdepicted in FIG. 8A after one actuation cycle;

FIG. 9 is a schematic perspective view of the rigid straight portionincluding first and second restraining elements;

FIG. 10 is a schematic end view of the rigid straight portion depictedin FIG. 9;

FIG. 11 is a schematic side view of the rigid straight portion depictedin FIG. 9;

FIG. 12 is a schematic side view of the rigid straight portion depictedin FIG. 11 rotated 120°;

FIG. 13A is a cross-sectional view of the elongated shaft assembly,reciprocating driveshaft, and fasteners in the unactuated position;

FIG. 13B is a cross-sectional view of the elongated shaft assembly,reciprocating driveshaft, and fasteners depicted in FIG. 13A in theactuated position;

FIG. 13C is a cross-sectional view of the elongated shaft assembly,reciprocating driveshaft, and fasteners depicted in FIG. 13A afteractuation;

FIG. 14 is a schematic exploded view of the elongated shaft assembly andthe reciprocating driveshaft including a stack of fasteners;

FIG. 15 is a schematic top view of a fastener;

FIG. 16 is a schematic bottom view of the fastener depicted in FIG. 16;

FIG. 17 is a schematic perspective view of the fastener depicted in FIG.16;

FIG. 18 is a schematic end view of the reciprocating driveshaftincluding a stack of fasteners disposed therein; and

FIG. 19 is a schematic end view of the elongated shaft assembly with thereciprocating driveshaft and stack of fasteners disposed therein.

DETAILED DESCRIPTION

The inventors have recognized that the application of excessive force toa stack of fasteners during actuation, as well as relative motion, suchas rotation, between adjacent fasteners, may interfere with fastenerdeployment.

In view of the above, the inventors have recognized the benefitsassociated with providing a controlled force to a stack of fasteners tofacilitate fastener deployment. Further, in some embodiments this forcemay be less than about the actuation force applied to a fastener locatedin a distal fastener deployment position. The inventors have alsorecognized several benefits associated with maintaining the orientationof the individual fasteners within the stack of fasteners and retaininga distal most fastener in a fastener deployment position. The abovenoted benefits may also lead to improved consistency in fastenerdeployment and surgical instrument operation.

In one embodiment, the surgical instrument may include a handle and anelongated shaft assembly extending distally from the handle. Theelongated shaft assembly may include a distally located fastenerdeployment position from which a fastener may be deployed. The surgicalinstrument may also include a fastener deployment system to deploy afastener from the fastener deployment position out of the distal end ofthe elongated shaft assembly. The fastener deployment system may beembodied in any number of ways. Further, in some embodiments, thefastener deployment system may include a magazine, or other appropriatestructure for containing a plurality of fasteners. Depending upon theparticular embodiment, the plurality of fasteners may be arranged as anested stack of fasteners, though other arrangements are alsoenvisioned. The fastener deployment system may also include a follower,or other appropriate component, that is associated with the stack offasteners such that it displaces one or more fasteners towards thefastener deployment position during an actuation cycle of the fastenerdeployment system.

In addition to deploying the fastener, actuation of the fastenerdeployment system may also result in the distal displacement of thefollower to distally displace the stack of fasteners towards thefastener deployment position and position a next distal most fastener inthe fastener deployment position. The fastener deployment system maydisplace the follower in any appropriate fashion. For example, in oneembodiment, the follower may be associated with a driveshaft of thefastener deployment system such that distal displacement of thedriveshaft distally displaces the follower. Backwards movement of thefollower may also be prevented through the use of an appropriateanti-backup element associated with the follower. Regardless of thespecific manner in which the follower is displaced, the follower may bearranged and adapted to provide a controlled force to the stack offasteners during displacement. The force applied to the stack offasteners may be any appropriate force, and in one embodiment may beless than the actuation force applied to deploy a fastener from thefastener deployment position.

In certain embodiments, the follower may be constructed in anyappropriate fashion such that it applies similar forces to the stack offasteners during subsequent actuation cycles of the fastener deploymentsystem. For example, the follower may include a driven element which isassociated with the fastener deployment system such that actuation ofthe fastener deployment system distally displaces the driven element.The driven element may also be associated with a compressible elasticelement which is associated with a pushing element. The elastic elementmay be adapted and arranged to provide a controlled force to the pushingelement upon displacement of the driven element. The elastic element maycomprise a coil spring, a conical spring, a pneumatic spring, anappropriately shaped component made of a compressible material (e.g.rubber), or any other appropriately shaped and sized compressiblecomponent capable of applying a force to the stack of fasteners when itis compressed. In some embodiments, in addition to providing acontrollable force to the stack of fasteners, the elastic element may besufficiently flexible to permit the follower to pass through anarticulated portion of the elongated shaft assembly while still applyinga force to the stack of fasteners. In such an embodiment, the drivenelement, elastic element, and pushing element may also be sized andshaped to pass through the elongated shaft assembly in both the straightand articulated configuration.

While the embodiments described herein refer to, and depict, the drivenelement, elastic element, and pushing element as separate componentsthat are physically associated with one another, the current disclosureis not limited to the use of separate components. For example, in someembodiments, the driven element, elastic element, and pushing elementmay be provided as part of an integral component.

In some embodiments, the follower may be adapted to provide similarforces to the stack of fasteners during subsequent actuation cycles.While this may be accomplished in any number of ways, in one embodiment,the follower may operate in the following manner. Upon actuation of thefastener deployment system, the driven element may be distallydisplaced. The distal displacement of the driven element may compressthe elastic element from a first length to a compressed second length.Subsequent to compressing the elastic element, the elastic element mayexpand from the compressed second length to the original first length.As the elastic element expands to the second length, the fasteners maybe distally displaced along the elongated shaft assembly towards thefastener deployment position. In some embodiments, the differencebetween the first length and the second length may correspond to thelength of one fastener. When the elastic element is in the expandedstate corresponding to the first length, the elastic element mayapplying a first force to the pushing element and the stack offasteners. Subsequently, when the elastic element is in the compressedstate corresponding to the second length, the elastic element mayapplying a second force to the pushing element and the stack offasteners. As would be expected for a compressed elastic element, thesecond force is greater than the first force. In some embodiments, thefirst force may be approximately zero. However, in other embodiments, itmay be desirable to provide a distal bias to the stack of fastenersthroughout the actuation cycle to prevent backwards movement of thestack of fasteners. In such an embodiment, the first force may greaterthan zero corresponding to an initial compression of the elastic elementprior to actuation of the fastener deployment system.

In addition to the forces applied to the stack of fasteners by thefollower, restraining forces may also be applied to the stack fastenersto prevent distal movement of the fasteners until the force applied bythe follower exceeds a preselected threshold force. For example, a firstrestraining force may be applied to the stack of fasteners prior to, andduring, actuation of the fastener deployment system. The firstrestraining force may be applied to the stack of fasteners to oppose thefirst force applied to the stack of fasteners by the follower.Consequently, prior to actuation of the fastener deployment system, thestack of fasteners may remain stationary within the elongated shaftassembly. However, during actuation, the elastic element may becompressed to a second compressed length to apply a greater force to thestack of fasteners as noted above. Once the applied force (e.g. thesecond force) is greater than the first restraining force, the stack offasteners may be distally displaced by the follower to position the nextfastener in the fastener deployment position. A second restraining forcemay subsequently be applied to restrain the stack of fasteners fromadditional distal movement during that actuation cycle.

Each of the noted restraining force may be provided by one or morerestraining elements. Further, the restraining elements may be embodiedin any number of fashions. For example, the restraining elements mayinclude: one or more tabs that extend inwards and distally relative tothe elongated shaft assembly; detent mechanisms; and other appropriatefeatures. Further, the restraining elements may be integrally formedwith the elongated shaft assembly, or the restraining elements may beformed separately and subsequently assembled with the elongated shaftassembly using any appropriate fashion including, but not limited to,welding, soldering, brazing, adhesives, mechanical couplings, fasteners,and interference fits.

In some embodiments, in addition to providing the restraining forces tothe stack of fasteners, the restraining elements may also be used todefine the fastener deployment position. For example, a head, or otherappropriate feature, of a fastener may be retained between the first andsecond restraining elements to define the fastener deployment position.

In addition to providing a follower to control the forces applied to thestack of fasteners, as noted above, it may be desirable to provide amechanism for maintaining the orientation of the fasteners within theelongated shaft assembly as the stack of fasteners is displaced towardsthe fastener deployment position by the follower. In one embodiment, aguide surface may be sized and shaped to interact with a correspondingsurface on at least a portion of the fasteners to maintain theorientation of the fasteners as they move within the elongated shaftassembly. In some instances, the corresponding surface on the fastenermay be shaped such that it is complementary both in shape and size tothe guide surface. The guide surface may be positioned on anyappropriate component of the elongated shaft assembly, or a componentthat is disposed within the elongated shaft assembly, that interactswith the fasteners as they are moved through the elongated shaftassembly. Further, the guide surface may extend along a distal portionof the component, a portion of the component corresponding to the stackof fasteners, or the entire length of the component as the currentdisclosure is not limited as to the location and extent of the guidesurface.

It should be understood that the guide surface and the correspondingsurfaces on the fasteners may include any combination of appropriateshapes and/or features that are capable of maintaining the orientationof the fasteners. For example, the guide surface and the correspondingsurfaces on the fasteners might include: corresponding flats; aprotrusion and corresponding groove; and other complementary arrangementas would be apparent to one of ordinary skill in the art.

In one particular embodiment, the fasteners may be disposed within aninternal channel of a reciprocating driveshaft that reciprocates in aproximal and distal direction. Further, the guide surface might beincorporated with the interior surface of the channel. In such anembodiment, the guide surface may interact with the correspondingsurface of the fasteners to maintain an orientation of the fastenerswithin the reciprocating driveshaft. During actuation of the fastenerdeployment system, the driveshaft may be moved in a distal direction todeploy a fastener prior to moving in a proximal direction in preparationfor the next actuation cycle. During this reciprocating movement of thedriveshaft, the driveshaft may be moved relative to the stack offasteners. Additionally, during, or subsequent to deployment of thefastener, the stack of fasteners may be displaced towards the distal endof the driveshaft to position the next distal most fastener in thefastener deployment position using any appropriate biasing element. Forexample, the stack of fasteners might be displaced using a follower asdescribed herein. As the stack fasteners are displaced towards thefastener deployment position, and as the driveshaft is moved relative tothe stack of fasteners disposed therein, the guide surface may maintainthe fasteners in a preselected orientation relative to one another andthe driveshaft. As previously noted, maintaining the fasteners in apreselected orientation relative to one another and the driveshaftensures proper alignment of the fasteners and may lower the necessaryforce to move the fasteners through an articulated portion of theelongated shaft assembly.

For the sake of clarity, the currently disclosed embodiments aredirected to a laparoscopic device. However, the current disclosure isnot limited to laparoscopic devices. Instead, the currently disclosedfollowers, restraining elements, and guide surfaces could be used in anyappropriate device for the deployment of a fastener into tissue. Forexample, any of the currently disclosed components, or combination ofdisclosed components, could be incorporated into an endoscopic device, aborescopic device, a catheter, a surgical instrument for use in “open”procedures, or any other appropriate surgical instrument. Additionally,the surgical instrument may be loaded with one or more fasteners priorto being provided to an end user, or it may be constructed to allow theuser to load the instrument with one or more fasteners. Further, whilethe various embodiments depicted herein are described as being used witha specific fastener, any appropriate fastener could be used with thecurrently disclosed embodiments including a tack, a clip, a staple, apin, a tissue anchor, a bone anchor, or any other appropriate type offastener.

Turning now to the figures, specific embodiments of the surgicalinstrument are described.

FIG. 1 presents one embodiment of a surgical instrument 2. The surgicalinstrument includes a handle 4 and an elongated shaft assembly 6extending distally from the handle 4. In addition to fasteners beingdeployed from a distal end of the elongated shaft assembly, theelongated shaft assembly 6 may include an articulable portion 8. Thesurgical instrument 2 may also include a trigger 14 to actuate anassociated fastener deployment system 15, see FIG. 2, and deploy afastener into tissue.

The articulable portion 8 may be articulated between a first position,such as an unarticulated (i.e. straight) position, and a secondposition, such as a fully articulated position, using the articulationcontrol 10. In some embodiments, the articulable portion 8 may bearticulated only between the first and second positions. In otherembodiments, the articulable portion 8 may be articulated to one or morepreselected articulated positions, or any arbitrary (i.e. notpreselected) articulated position as the current disclosure is notlimited in this fashion. Further, depending upon the embodiment, thearticulable portion 8 may only be articulated in one direction, or itmay be articulated in two directions. For example, the articulableportion 8 may be articulated between approximately 0° and 90°, 0° and45°, −90° and 90°, −180° and 180° or any other appropriate range ofangles. In addition, in some embodiments the articulable portion 8 mayarticulate about two different axes (e.g. articulation in the horizontaldirection and vertical direction).

In some embodiments, it may be, desirable to rotate the elongated shaftassembly 6 to facilitate positioning of the distal tip. One suchembodiment is depicted in FIGS. 1 and 12. The rotation of the elongatedshaft assembly 6 may be provided in any appropriate manner. For example,the elongated shaft assembly 6 may simply be adapted to be rotatable toat least a portion of the handle 4. Alternatively, a portion of thehandle 4 including the elongated shaft assembly 6 may be rotatablerelative to another portion of the handle 4, such as the portionincluding the grip. One such embodiment is depicted in FIG. 1. In thedepicted embodiment, the surgical instrument 2 includes a first handleportion 16 and a second handle portion 18 including the elongated shaftassembly 6. The first and second handle portions 16 and 18 may beconstructed and arranged in any appropriate fashion to be rotatablerelative to one another. It should be understood that while a surgicalinstrument including a rotatable elongated shaft assembly 6 or handle 4is depicted in the figures, a surgical instrument including a unitaryhandle and/or an elongated shaft assembly 6 that is stationary relativeto the handle are also possible as the current disclosure is not limitedin this manner.

In certain applications, it may be advantageous to include a rigidstraight portion 12 distally located from the articulable portion 8. Forexample, and without wishing to be bound by theory, when a driveshaftapplies a force to a fastener as it goes around a curve, the forceapplied by the driveshaft to a proximal portion of the fastener may notbe aligned with the deployment direction of the fastener. This mayresult in a portion of the applied force being directed against a sideof the elongated shaft assembly 6. In contrast, when a driveshaftapplies a force to a fastener along a straight section, the appliedforce is aligned with the deployment direction of the fastener. Thus,including a rigid straight portion 12 that distally extends from thearticulable portion 8 for a given length may enable the driveshaft toapply a reduced actuation force to deploy the fastener since the appliedactuation force may be aligned with the deployment direction. Further,applying an actuation force that is aligned with the deploymentdirection may also improve the consistency of fastener deployment as thesurgical instrument is varied between different articulation angles. Inaddition to the benefits noted above, the rigid straight portion 12 mayalso incorporate other components or features to aid in the positioningand deployment of a fastener from the surgical instrument. While asurgical instrument 2 including a distal rigid straight portion 12 hasbeen described herein, and depicted in figures, it should be understoodthat embodiments are also envisioned in which the articulable portion 8extends all the way to the distal end of the elongated shaft assembly 6such that the surgical instrument does not include a distal rigidstraight portion.

As noted previously, the surgical instrument 2 may also include afastener deployment system 15 as depicted in FIG. 2. The fastenerdeployment system 15 may be embodied in any number of different ways.However, in the particular embodiment depicted in FIG. 2 the fastenerdeployment system may include a trigger 14, a rigid linkage 20, ashuttle 22, a power assist device 24, and a reciprocating driveshaft 26as well as other components that are not depicted. Actuation of thetrigger 14 may distally displace the rigid linkage 20 to distallydisplace the shuttle 20 and store energy in the power assist device 24.After a preselected amount of actuation, the power assist device 24 mayrelease the stored energy to distally accelerate the driveshaft 26 anddeploy a fastener from the distal end of the elongated shaft assembly 6.

While a particular power assist device 24 is depicted, the power assistdevice 24 may correspond to any appropriate construction capable ofaiding in deploying a fastener from the elongated shaft assembly 6 ofthe surgical instrument. Depending on the particular embodiment, thepower assist device 24 may supply all of the power necessary to deploy afastener in response to actuation of the trigger 14, or it may onlysupply a portion of the power necessary to deploy a fastener. In onespecific embodiment, the power assist device 24 may correspond to thepower assist device disclosed in application Ser. No. 13/804,043entitled POWER ASSIST DEVICE FOR A SURGICAL INSTRUMENT filed on the sameday as the current application. While a surgical instrument including apower assist device has been depicted, in some embodiments, the surgicalinstrument 2 may not include a power assist device, in which caseactuation of the trigger 12 might displace driveshaft 26, eitherdirectly or indirectly through the use of an appropriate transmission,to deploy a fastener from a distal end of the elongated shaft assembly6.

FIG. 3 presents an exploded view of one embodiment of the elongatedshaft assembly 6 and the various components disposed within theelongated shaft assembly. In the depicted embodiment, the driveshaft 26is located within the elongated shaft assembly 6. As illustrated byFIGS. 2 and 3, when disposed within the elongated shaft assembly 6, thedriveshaft 26 extends proximally from the elongated shaft assembly 6into the handle 4. The surgical instrument also includes a stack offasteners 28, a follower 34, and an anti-backup element disposed withinan internal channel of the driveshaft 26. The stack of fasteners 28 mayinclude one or more fasteners 30, and in some instances may be aplurality of fasteners 30.

In addition to the above components, the surgical instrument may alsoinclude a fastener guide 32 to help maintain the alignment of the stackof fasteners 28, the follower 34, and the anti-backup element 36 withinthe internal channel of the driveshaft 26. While any appropriatestructure may be used, in the depicted embodiment, the fastener guide 32is a distally extending wire positioned in approximately the center ofthe channel of the driveshaft. The fastener guide 32 may be retainedwithin the channel in any appropriate fashion. For example, the fastenerguide 32 may be attached to a portion of the anti-backup element 36, aportion of the handle 4, or any other appropriate structure. Further,the faster guide 32 may be attached using any appropriate methodincluding, but not limited to, adhesives, mechanical interference,clamping, soldering, brazing, and welding.

Upon actuation of the trigger, the fastener deployment system may beactuated resulting in a distal displacement of the driveshaft 26. Asdescribed in more detail below, a distal displacement of the driveshaft26 deploys a distal most fastener located in the fastener deploymentposition. The driveshaft 26 also distally displaces the follower 34 todisplace the stack of fasteners 28 and position the next distal mostfastener in the fastener deployment position. The follower 34 andanti-backup element 36 may be associated such that a distal displacementof the following 34 results in the anti-backup element extending in thedistal direction to prevent a proximal movement of the follower 34.After deployment of a fastener, and positioning of the next fastener inthe fastener deployment position, the driveshaft 26 may be moved in aproximal direction to prepare the surgical instrument for the nextactuation while preventing proximal movement of the stack of fasteners28, the follower 34, and the anti-backup element 36.

The interaction between the follower 34 and the driveshaft 26 isdepicted in FIGS. 4-6.

In the depicted embodiment, the follower 34 includes a driven element100, an elastic element 102, and a pushing element 104. The drivenelement 100 is adapted to interact with the driveshaft 26 to displacethe follower 34 in a distal direction. The driven element 100 includestabs 106 which interact with openings 124 on the driveshaft 26. The tabs106 may be flexible and extend outwards and distally from the drivenelement 100. In addition, the tabs 106 may be sized, shaped, andarranged such that the tabs 106 may be disposed within the openings 124as the driven element 100 is distally moved through driveshaft 26.Driven element 100 may also include a distal portion 108 a as well as ashoulder 110. The distal portion 108 a and the shoulder 110 may be sizedand shaped to retain a distal end of the elastic element 102 on thedistal portion 108 a. The distal portion 108 a may also include one ormore retention features 116. The depicted retention features 116 areprotrusions located on the distal portion 108 a that interfere with theelastic element 102 to retain the elastic element thereon.Alternatively, the elastic element 102 might be retained on the drivenelement 100 using any appropriate method including, but not limited to,mechanical interference, interlocking features, adhesives, welding,soldering, and brazing. The driven element 100 may also include acoupling 118 located on a proximal portion 108 b. The coupling 118 maybe adapted and arranged to attach the follower 34 to the anti-backupelement 36.

The depicted elastic element 102 is a coil spring that extends betweenthe driven element 100 and the pushing element 104. As noted above,while a coil spring has been depicted, other springs and appropriatecomponents could be used in place of a coil spring. Regardless of thespecific component used as the elastic element 102, the elastic element102 may be sized, shaped, and arranged to be associated with both thedriven element 100 and the pushing element 104. Further, due to the useof a spring, or other appropriate compressible component, as the drivenelement is moved in a distal direction, the elastic element 102 iscompressed to apply a force to the pushing element 104. Largerdisplacements of the driven element 100 prior to movement of the pushingelement 104 may result in larger compressions of the elastic element 102and correspondingly larger forces. Depending upon the particularembodiment, the elastic element 102 may exhibit a linear force todisplacement relationship, or a nonlinear force to displacementrelationship, as the current disclosure is not limited in this fashion.

Similar to the driven element 100, pushing element 104 may include aproximal portion 112 b and a shoulder 114 that are sized and shaped toretain a distal end of the elastic element 102. The pushing element 104may also include one or more retention features 116 for retaining theelastic element 102 similar to those described above for the drivenelement 100. The pushing element 104 may also include a distal portion112 a that is adapted and arranged to apply a force to the mostproximally located fastener of the fastener stack. In some embodiments,the distal portion 112 a may directly contact at least the proximal mostfastener in the stack of fasteners, though embodiments in which thedistal portion 112 a indirectly applies a force to the stack offasteners are also envisioned.

As depicted in FIG. 5, the driveshaft 26 may include one or morefastener driving elements 120 located on the distal end of thedriveshaft 26. In some embodiments, the fastener driving element 120 maybe one or more flexible tabs that extend inwards and distally from thedistal end of the driveshaft 26. The fastener driving elements 120 maybe adapted to apply a force to a fastener located in the fastenerdeployment position to deploy the fastener from the distal end of theelongated shaft assembly. The driveshaft may also include a flexibleportion 122 to accommodate movement of the reciprocating driveshaftthrough the articulable portion of the elongated shaft assembly. In thedepicted embodiment, the flexible portion 122 is formed by providing apattern of slots, or cuts, in the driveshaft 26. As noted above, thedriveshaft 26 may also include openings 124 that are sized and shaped toaccommodate the tabs 106 of the driven element 100 in an expandedposition. One or more sets of openings 124 may be axially spaced alongone or more surfaces of the driveshaft 124. In some embodiments, theaxial spacing between the openings 124 may correspond to the length of asingle fastener. In the current embodiment, two sets of openings 124extend along opposite sides of the driveshaft 26 to accommodate both ofthe tabs 106 of the driven element 100. The openings 124 may extendalong the entirety of driveshaft 24, or as depicted in the figures, theopenings 124 may extend along a portion of the driveshaft 24corresponding to an initial proximal position of the follower 34 and afinal distal position of the follower 34 after all of the fasteners havebeen deployed from the surgical instrument.

Having described the corresponding features on the driveshaft 26 and thefollower 34, the interactions of these two components during actuationin one possible embodiment will now be described, see FIG. 6. Prior toactuation, the tabs 106 of the driven element 100 may be located in theexpanded state in any one of the corresponding openings 124 of thedriveshaft 26. While the tabs 106 are in the expanded state within acorresponding opening 124, a proximal portion of the driveshaft 124 a,such as a proximal edge of the opening may be axially aligned with aproximal aspect 106 a of a tab 106. Consequently, as the driveshaft 26is moved in a distal direction during actuation, the proximal driveshaftportion 124 a applies a distally directed force to the proximal aspect106 a of the tabs 106 resulting in a distal displacement of the drivenelement 100. After the fastener has been deployed, the driveshaft 26 issubsequently moved in a proximal direction. During the proximal movementof the driveshaft 26, a distal portion of the shaft 124 b, such as adistal edge of the openings 124, may be drawn over an exterior aspect106 b, such as an exterior surface, of the tabs. As described in moredetail below, the driven element 100 may be prevented from movingbackwards during the relative movement of the driveshaft 26 and thedriven element 100. Further, as noted above, the tabs 106 are flexible.Thus, as the distal driveshaft portion 124 b is drawn over the exterioraspect 106 b of the tabs, the tabs 106 may be displaced inwards and outof the openings 124 to permit the relative movement of the drivenelement 100 and the driveshaft 26. The proximal displacement of thedriveshaft 26 may be continued until the tabs 106 are aligned with thenext distally located set of openings 124 and the tabs 106 are in theexpanded state within the openings 124. Subsequent actuation cycles mayresult in the driven element 100 progressively moving in a distaldirection as the driven element 100 engages with the next correspondingset of openings 124 of the driveshaft. In view of the above, the drivenelement 100 of the follower 34 and the driveshaft 26 may be described asforming two separate components of a walking beam assembly that isconfigured to sequentially displace the follower 34 in a distaldirection during each actuation cycle of the fastener deployment system.

FIGS. 7A-7B depict the interaction of the stack of fasteners 28, thefollower 34, and the anti-backup element 36 during an actuation cycle ofthe fastener deployment system. As illustrated in the figures, thepushing element 104 may be in contact with a proximally located fastenerof the fastener stack 28. The elastic element 102 may also be associatedwith a proximal portion of the pushing element 104 and a distal portionof the driven element 100. The driven element 100 may be coupled to arack arm 126 of the anti-backup element 36 by a coupling 130. The drivenelement 100 and rack arm 126 may be coupled in such a manner that distalmovement of the driven element 100 may result in the distal extension ofthe rack arm 126 relative to a pawl arm 128 of the anti-backup element36. Thus, as the follower 34 is distally displaced through the elongatedshaft assembly, the anti-backup element 36 correspondingly elongates.Consequently proximal movement of the follower 34 may be prevented bythe anti-backup element 36 throughout the actuation cycle. As depictedin the figures, coupling 130 corresponds to a pin connection. However,any appropriate connection might be used including, but not limited to,interlocking mechanical features, a set screw, fasteners, adhesives,welding, brazing, and interference fits.

Prior to actuation, as depicted in FIG. 7A, the elastic element 102 ofthe follower 34 is in the expanded state corresponding to the firstlength and may apply a first distally directed force to the distallylocated pushing element 104 and the stack of fasteners 28. The follower34 and the stack of fasteners 28 are prevented from moving in a distaldirection by the anti-backup element 36. In the depicted embodiment, theanti-backup element 36 includes a rack arm 126 which may be moved in thedistal direction, and a pawl arm 128 which remains stationary duringactuation of the surgical instrument.

Referring to FIG. 7B, as the fastener deployment system is actuated, thedriveshaft, not depicted, may apply a force F_(D) to the tabs 106 of thedriven element 100 which drives the driven element 100 in a distaldirection as described above. A proximally directed first restrainingforce F_(R1) may be applied to the stack of fasteners 28. Initially, thefirst restraining force F_(R1) may be equal to force F_(D). Thus, duringthe initial portions of actuation, the stack of fasteners 28 may remainstationary resulting in the compression of elastic element 102 betweenthe pushing element 104 and the driven element 100. As actuationcontinues, the force applied to the driven element 100 may continue toincrease as the elastic element 102 is further compressed. Thiscontinued compression of the elastic element 102 applies an increasingdistally directed force to the stack of fasteners 28. At some pointduring actuation, the spring may be compressed to a second lengthcorresponding to the elastic element 102 applying a second distallydirected force to the pushing element 104 and the associated stack offasteners 28. This second distally directed force may be greater thanthe first restraining force F_(R1) resulting in the expansion of theelastic element 102 and distal displacement of the pushing element 104and associated stack of fasteners 28, see FIGS. 7B-7C.

As depicted by the figures, the elastic element 102 continues to expandfrom the second length to the first length as the stack of fasteners 28is displaced in the distal direction. As the elastic element 102approaches the expanded first length, a proximally directed secondrestraining force F_(R2) may be applied to the stack of fasteners 28 toprevent further distal movement of the stack of fasteners. The secondrestraining force F_(R2) may be greater than the first restraining forceto oppose both the force applied to the stack of fasteners 28 by theelastic element 102 as well as possible kinetic energy stored in thestack of fasteners 28 and follower 34 as they are being distallydisplaced. The second restraining force may also be less than theactuation force to deploy a fastener from the elongated shaft assembly.In some embodiments, the second restraining force F_(R2) may be appliedonce a distally located fastener of the stack fasteners 20 has beenpositioned in the fastener appointment position. After the stack offasteners 28 has been distally displaced and the fastener deploymentsystem has been reset, the surgical instrument may be actuated againresulting in further distal displacement of the follower 34 and theassociated stack of fasteners 28.

In addition to displacement of the follower 34 and the associated stackof fasteners 28, actuation of the fastener deployment system may alsoresult in an extension of the anti-backup element 36 as noted above.More specifically, due to the driven element 100 and the rack arm 126being coupled, distal displacement of the driven element 100 may resultin a corresponding distal displacement of the rack arm 126 relative tothe pawl arm 128. The distal movement of the rack arm 126 may extend theanti-backup element 36 in a distal direction to prevent backwardsmovement of the driven element 100 after the stack of fasteners 28 hasbeen distally displaced. The interactions of the rack arm 126 and thepawl arm 128 are illustrated in more detail in FIGS. 8A and 8B. Teeth134 may be spaced along the axial length of the rack arm 126. Acorresponding pawl 132 may be positioned on a distal portion of the pawlarm 128. The pawl 132 and the corresponding teeth 134 may be adapted andarranged to permit distal movement of the rack arm 126 in response todistal movement of the driven element. The pawl 132 and thecorresponding teeth 134 may also be adapted and arranged to preventproximal movement of the rack arm 126. In one embodiment, the distancebetween the teeth 134 may be approximately equal to one fastener length.However, embodiments in which the distance between teeth 134 is afraction of a fastener length, or greater than a fastener length, arealso envisioned. In addition to the above, while a rack and pawl systemhave been depicted for the anti-backup element 36, any appropriatemechanism capable of preventing backwards movement of the follower andthe stack fasteners could be used.

FIGS. 9-12 depict an inner tubular member 200 which is a component ofthe elongated shaft assembly 6. The inner tubular member 200 includesthe rigid straight portion 12 which forms the distal end of theelongated shaft assembly 6. The inner tubular member may also includeone or more first restraining elements 202 and one or more secondrestraining elements 204 located within the rigid straight portion 12.As depicted in FIG. 9, the two second restraining elements 204 aredistally located relative to a first restraining elements 202. The firstrestraining element may be adapted and arranged to provide the firstrestraining force to the stack of fasteners during actuation.Correspondingly, the second restraining elements 204 may be adapted andarranged to provide the second restraining force to the stack fastenersduring actuation. As noted previously, the first restraining force maybe less than the second restraining force. The different restrainingforces may be provided in any number of ways as the current disclosureis not limited to the manner in which the restraining forces are appliedto the stack of fasteners. In some embodiments the restraining elementsmay be integrally formed with elongated shaft assembly, or a componentof the elongated shaft assembly. Alternatively, the restraining elementsmay be formed separately and assembled with elongated shaft assembly inany appropriate fashion including, but not limited to, welding,soldering, brazing, adhesives, interference fits, and fasteners.

The different first and second restraining forces may be provided in anyappropriate manner. For example, in one embodiment, differentcompliances of the first and second restraining elements may be used toprovide the different first and second restraining forces. Morespecifically, the second restraining elements may be less compliant thanthe first restraining elements. In another embodiment, the differentfirst and second restraining forces may be provided using differentnumbers of the first and second restraining elements. In such anembodiment, a greater number of the second restraining elements may beused as compared to the number of first restraining elements. Whilespecific methods of providing the different restraining forces have beennoted above, other ways of providing the restraining forces are alsocontemplated.

In one possible embodiment, and as depicted in FIGS. 9-12, the first andsecond restraining elements 202 and 204 may correspond to tabs thatextend inwards and distally relative to the inner tubular member 200 ofthe elongated shaft assembly. To provide the desired first and secondrestraining forces, a single more compliant first restraining element202 and two less compliant second restraining elements 204 areincorporated into the rigid straight portion 12 of the inner tubularmember 200 of the elongated shaft assembly. The tabs corresponding tothe second restraining elements 204 may have reduced lengths and/orincreased widths as compared to the tab corresponding to the firstrestraining element 202. Without wishing to be bound by theory, thisresults in the second restraining elements 204 being less compliant thanthe first restraining element 202. Consequently, due to the use of twoless compliant tabs for the second restraining elements 204 as comparedto a single more compliant tab for the first restraining element 202,the depicted embodiment is adapted to provide a second restraining forcethat is greater than the first restraining force. It should beunderstood that while a particular arrangement of first and secondrestraining elements has been depicted in the figures and describedabove, other embodiments for providing the first and second restrainingforces are also possible.

The interaction between the first restraining elements 202, the secondrestraining elements 204, the fasteners 30, and the driveshaft 26 of thefastener deployment system are illustrated by FIGS. 13A-13C depicting aseries of cross-sections of a distal portion of the elongated shaftassembly 6 during actuation of the fastener deployment system. Prior toactuation, a distally located fastener 30 is positioned in the fastenerdeployment position 206. The fastener deployment position 206 may bedefined by the relative locations of the first restraining elements 202and the second restraining elements 204. The first restraining elements202 and the second restraining elements 204 may define the fastenerdeployment position by retaining the head 30 a of a fastener 30 betweenthem prior to actuation. Retaining a fastener 30 in the fastenerdeployment position 206 using the restraining elements 202 and 204 maybeneficially prevent a fastener from inadvertently being displaced outof the elongated shaft assembly 6 as well as providing a consistentposition of a fastener for subsequent deployment. Upon actuation of thefastener deployment system, the driveshaft 26 is distally displacedresulting in the fastener driving elements 120 applying a force to thefastener 30 located in the fastener deployment position 206. The appliedactuation force is greater than the second restraining force provided bythe second restraining elements 204 resulting in the distal displacementand deployment of the fastener as depicted in FIG. 13B. As noted above,the stack of fasteners may have a separate force applied to distallydisplace the stack of fasteners and position the next fastener in thefastener deployment position 206 for the next actuation cycle. As thedriveshaft 26 is withdrawn in a proximal direction to reset the fastenerdeployment system for the next actuation cycle, the fastener drivingelements 120 deform around and past the head 30 a of the fastener 30located in the fastener deployment position 206, see FIG. 13C. Asdepicted in the figure, the tabs corresponding to the first and secondrestraining elements 202 and 204 may be arranged and adapted to resistproximal movement of a fastener 30 located distally from the restrainingelements 202 and 204. Consequently, proximal movement of a fastener 30located in the fastener deployment position 206 may be prevented by thefirst restraining element 202 as the driveshaft is moved in the proximaldirection. Once the driveshaft 26 has been fully moved in the proximaldirection, the surgical instrument is ready to deploy the next fastener.

While the above described embodiments have been directed to a followerthat is driven by the reciprocating action of a driveshaft in a proximaland distal direction, other embodiments are possible. For example, inone embodiment, the follower might be associated with a rotatingdriveshaft such that rotation of the driveshaft may result in a distaldisplacement of the follower and the associated fasteners disposedwithin the driveshaft. In another exemplary embodiment, the followermight be associated with another component of the fastener deploymentsystem such that actuation of the fastener deployment system results ina distal movement of the follower. For example, the follower might beassociated with the trigger 14, the rigid linkage 20, or the shuttle 22.Further, the follower may be directly, or indirectly, associated withany of the above components.

As noted previously, in addition to displacing the stack of fasteners toposition the next fastener in the fastener deployment position, in someembodiments, it may be desirable to maintain a particular orientation ofthe fasteners within the elongated shaft assembly. FIG. 14 depicts aschematic exploded view of the elongated shaft assembly 6 and thedriveshaft 26 which may be disposed within the interior of the elongatedshaft assembly 6. The depicted pattern of slots formed in the exteriorof the elongated shaft assembly 6 impart flexibility to the portion ofthe elongated shaft assembly 6 corresponding to the articulable portion8. In the depicted embodiment, the driveshaft includes an internalchannel to accommodate one or more fasteners 30 disposed therein. Thedriveshaft 26 may also include a guide surface 136. The guide surface136 may be any appropriate shape, and as depicted in the figure, maycorrespond to a flat extending along the axial direction of thedriveshaft 26. The guide surface 136 may interact with a correspondingsurface on the fasteners 30 to maintain an orientation of the fastenerswhile they are disposed within the driveshaft 26 and as the driveshaftreciprocates between a distal position and a proximal position duringactuation. In addition to the guide surface 136, the driveshaft 26 mayalso include a fastener driving element 120 a that interacts with thecorresponding surface on the fasteners 30 to maintain the orientation ofa fastener 30 as it is positioned in the fastener deployment position.

In the depicted embodiment, a flat corresponding to the guide surface136 is present on an internal surface of the internal channel of thedriveshaft 26. Additionally, the guide surface 136 may optionally bepresent on an exterior surface of the driveshaft 26 as well. While aparticular shape has been depicted for the guide surface 136, anyappropriate shape or combination of features could be present on thedriveshaft 26 to maintain an orientation of the fasteners 30 disposedtherein. For example, the guide surface 136 may correspond to aprotrusion, a groove, or any other appropriate shape. Further, the guidesurface 136 may extend along any appropriate portion of the driveshaft26. For example, the guide surface 136 might extend along a distalportion of the driveshaft, a flexible portion 122 of the driveshaft, aportion of the driveshaft corresponding to the stack of fastenerslocated within the driveshaft, or the entire length of the driveshaft asthe current disclosure is not limited in this fashion.

FIGS. 15-17 depict one possible embodiment of a fastener 30 for use withthe driveshaft 26. The depicted embodiment of the fastener 30 includes:a head 30 a; a shaft 30 b extending from the head 30 a; and a barbed end30 c located at a distal end of the shaft 30 b. A surface 138corresponding to the guide surface 136 of the driveshaft may be disposedon the head 30 a. The surface 138 may be sized and shaped to complementthe guide surface 136 the driveshaft such that the fastener 30 smoothlyinterfaces with the internal surfaces of the driveshaft 26. In thedepicted embodiment, the surface 138 corresponds to a flat such that across-section of the head 30 a includes a flat portion and a roundportion sized and shaped to complement corresponding flat and roundportions of a cross-section of the internal channel of the driveshaft.While the surface 138 corresponding to the guide surface 136 has beendepicted as being located on the head 30 a of the fastener, the surface138 might be located on any appropriate portion of the fastener 30. Forexample, a portion of the shaft 30 b or barbed end 30 c could include acorresponding surface, or feature, that is shaped, sized, and arrangedto interact with the guide surface 136 of the driveshaft to maintain anorientation of the fastener 30.

In addition to the surface 138 present on the fastener 30 whichcorresponds to the guide surface 136, the fastener 30 may also include athrough hole 140 extending distally from a proximal surface of the head30 a through the shaft 30 b and the barbed end 30 c. The through hole140 may be sized and shaped to accommodate the fastener guide, asdescribed above, to maintain the alignment of the fasteners 30 withinthe elongated shaft assembly. The through hole 140 may be centrallylocated, radially offset, or arranged in any other appropriate locationas the current disclosure is not limited as to where the through hole140 is located. While it may be desirable to include a through hole 140to help maintain the alignment of the fasteners 30 within the elongatedshaft assembly, it may also be desirable in certain embodiments toprovide a pointed tip 142 on the fastener as depicted in the figure.However, embodiments using a blunt tip and an associated piercing needleare also envisioned. To accommodate the through hole 140, the pointedtip 142 may be radially offset relative to the through hole 140.

FIG. 18 depicts a distally located fastener 30 disposed within theinternal channel 140 of the driveshaft 26. As illustrated by the figure,guide surface 136 and the fastener driving element 120 a of thedriveshaft 26 are aligned with the corresponding surface 138 of thefastener 30. Due to the interaction of the flat portions of the internalchannel cross-section and the fastener head (i.e. the guide surface 136and corresponding surface 138), as well as the round portions of theinternal channel cross-section and the fastener head, the fastener 30may be maintained in a preselected orientation throughout the length ofthe driveshaft 26.

FIG. 19 depicts the fastener 30 and driveshaft 26 of FIG. 18 disposedwithin the elongated shaft assembly 6. As best illustrated by FIG. 13B,in some embodiments, the fastener driving elements 120 may extenddistally relative to the first and second restraining elements 202 and204 when the driveshaft 26 is distally displaced to deploy a fastener.Consequently, it may be desirable to arrange the fastener drivingelements 120 and the first and second restraining elements 202 and 204such that they do not interfere with one another during distaldisplacement of the driveshaft. In the depicted embodiment, the fastenerdriving elements 120 are arranged in a triangular pattern at a distalend of the driveshaft 26 and the first and second restraining elements202 and 204 are arranged in another corresponding triangular patternaround the internal surface of the elongated shaft assembly 6 such thatthe fastener driving elements 122 do not interfere with the first andsecond restraining elements 202 and 204 during the distal displacementof the driveshaft. It should be understood that while a particularnumber and arrangement of the fastener driving elements and restrainingelements has been depicted in the figures and described herein, thecurrent disclosure is not limited in this manner. Instead, anyappropriate number and arrangement of fastener driving elements andrestraining elements might be used. Further, other appropriate types offastener driving elements and restraining elements might also be used.

While the present teachings have been described in conjunction withvarious embodiments and examples, it is not intended that the presentteachings be limited to such embodiments or examples. On the contrary,the present teachings encompass various alternatives, modifications, andequivalents, as will be appreciated by those of skill in the art.Accordingly, the foregoing description and drawings are by way ofexample only.

What is claimed is:
 1. A surgical instrument comprising: a handle; anelongated shaft assembly extending distally from the handle; a fastenerdeployment system for deploying fasteners from the elongated shaftassembly; and a follower disposed within the elongated shaft assemblyand associated with one or more fasteners disposed within the elongatedshaft assembly, wherein actuation of the fastener deployment systemcompresses the follower from a first length to a second length to applya distally directed force to the one or more fasteners and displace thefasteners in a distal direction, and wherein during displacement of theone or more fasteners the follower expands from the second length to thefirst length.
 2. The surgical instrument of claim 1, wherein thefollower comprises a driven element associated with the fastenerdeployment system, an elastic element, and a pushing element arrangedand adapted to apply a force to the one or more fasteners.
 3. Thesurgical instrument of claim 2, wherein the driven element, the elasticelement, and the pushing element are integrally formed.
 4. The surgicalinstrument of claim 2, wherein the elastic element is a coil spring. 5.The surgical instrument of claim 2, wherein the driven element and thefastener deployment system are configured as a walking beam.
 6. Thesurgical instrument of claim 1, wherein the first length of the followeris a first compressed length.
 7. The surgical instrument of claim 1,wherein the force applied to the one or more fasteners to displace theone or more fasteners is similar during each actuation cycle of thefastener deployment system.
 8. The surgical instrument of claim 1,wherein the follower is displaced by approximately a single fastenerlength during each actuation cycle of the fastener deployment system. 9.The surgical instrument of claim 1 further comprising an anti-backupelement to prevent proximal movement of the follower.
 10. The surgicalinstrument of claim 1, wherein the follower includes a flexible portionconfigured and adapted to permit the follower to conform to a shape ofthe elongated shaft assembly in an articulated position.
 11. A surgicalinstrument comprising: a handle; an elongated shaft assembly extendingdistally from the handle; a fastener deployment system for deployingfasteners from the elongated shaft assembly, wherein the fastenerdeployment system includes a driveshaft disposed within the elongatedshaft assembly; and a follower disposed within the elongated shaftassembly and associated with the driveshaft, wherein a distaldisplacement of the driveshaft deploys a fastener from the elongatedshaft assembly, wherein the distal displacement of the driveshaftdisplaces the follower in a distal direction to displace one or morefasteners disposed in the elongated shaft assembly in a distaldirection, wherein a force applied to the deployed fastener by thedriveshaft is greater than a force applied to the one or more fastenersby the follower.
 12. The surgical instrument of claim 11, wherein thefollower and the one or more fasteners are disposed in the driveshaft.13. The surgical instrument of claim 11, wherein the follower remainsstationary when the driveshaft is proximally displaced.
 14. The surgicalinstrument of claim 11, wherein the driveshaft displaces the follower byapproximately a single fastener length during each actuation cycle ofthe fastener deployment system.
 15. The surgical instrument of claim 11further comprising an anti-backup element to prevent proximal movementof the follower.
 16. A surgical instrument comprising: a handle; anelongated shaft assembly extending distally from the handle; a fastenerdeployment system for deploying fasteners from the elongated shaftassembly; and a follower disposed within the elongated shaft assemblyfor displacing one or more fasteners within the elongated shaft assemblyin a distal direction, wherein the follower applies a first force to theone or more fasteners prior to actuation of the fastener deploymentsystem and a second force to the one or more fasteners after actuationof the fastener deployment system is begun to displace the one or morefasteners in the distal direction, wherein the elongated shaft assemblyis configured to apply a first restraining force and a secondrestraining force to the one or more fasteners, wherein the first forceis less than the first restraining force, and wherein the second forceis greater than the first restraining force and less than the secondrestraining force.
 17. The surgical instrument of claim 16 furthercomprising a first restraining element associated with the elongatedshaft assembly to apply the first restraining force to the one or morefasteners and a second restraining element associated with the elongatedshaft assembly to apply the second restraining force to the one or morefasteners.
 18. The surgical instrument of claim 17, wherein the firstand second restraining elements comprise one or more tabs that extendinward and distally relative to the elongated shaft assembly.
 19. Thesurgical instrument of claim 17, wherein the first and secondrestraining elements are associated with a rigid straight portion of theelongated shaft assembly.
 20. The surgical instrument of claim 16,wherein the fastener deployment system applies a deployment force to afastener in a distal fastener deployment position that is greater thanthe second restraining force.
 21. The surgical instrument of claim 16further comprising an anti-backup element to prevent proximal movementof the follower.
 22. A surgical instrument comprising: a handle; anelongated shaft assembly extending distally from the handle; a firstrestraining element associated with the elongated shaft assembly; asecond restraining element associated with the elongated shaft assemblyand located distally from the first restraining element, wherein thefirst restraining element and the second restraining element define afastener deployment position; and a fastener deployment system fordeploying fasteners from the elongated shaft assembly, wherein thefastener deployment system includes a driveshaft adapted and arranged toapply a deployment force to a fastener located in the fastenerdeployment position.
 23. The surgical instrument of claim 22, whereinthe first restraining element and the second restraining elementcomprise one or more tabs that extent inward and distally relative tothe elongated shaft assembly.
 24. The surgical instrument of claim 22,wherein the first restraining element and the second restraining elementare integrally formed with the elongated shaft assembly.
 25. Thesurgical instrument of claim 22, wherein the driveshaft is distallydisplaced beyond the first restraining element and the secondrestraining element during actuation of the fastener deployment systemto deploy the fastener located in the fastener deployment position. 26.The surgical instrument of claim 25, where in the driveshaft isconstructed and arranged to avoid interference with the firstrestraining element and the second restraining element during actuationof the fastener deployment system.
 27. The surgical instrument of claim22 further comprising an anti-backup element to prevent proximalmovement of the follower.
 28. The surgical instrument of claim 22,wherein a first restraining force applied by the first restrainingelement to one or more fasteners located distally from the firstrestraining element is less than a second restraining force applied bythe second restraining element to the fastener located in the fastenerdeployment position.
 29. A method of operating a surgical instrument,the method comprising: providing: a handle; an elongated shaft assemblyextending distally from the handle; a fastener deployment system fordeploying fasteners from the elongated shaft assembly; and a followerdisposed within the elongated shaft assembly and associated with one ormore fasteners disposed within the elongated shaft assembly; actuatingthe fastener deployment system to deploy a fastener from the elongatedshaft assembly; distally displacing the follower to compress thefollower from a first length to a second length to apply a distallydirected force to one or more fasteners to displace the one or morefasteners in a distal direction, and wherein during displacement of theone or more fasteners the follower expands from the second length to thefirst length.
 30. The method of claim 29, wherein actuation of thefastener deployment system and displacement of the follower areconcurrent.
 31. The method of claim 29 further comprising preventingproximal movement of the follower.
 32. The method of claim 29, whereindistally displacing the follower comprises distally displacing thefollower by approximately a single fastener length during each actuationcycle of the fastener deployment system.
 33. The method of claim 29,wherein actuating the fastener deployment system distally displaces adriveshaft to deploy the fastener from the elongated shaft assembly anddistally displace the follower to compress the follower from the firstlength to the second length.
 34. A surgical instrument comprising: ahandle; an elongated shaft assembly extending distally from the handle;a fastener deployment system for deploying fasteners from the elongatedshaft assembly, wherein the fastener deployment system includes adriveshaft; and a follower configured to displace a stack of fasteners,wherein the follower is disposed within the driveshaft, wherein thefollower and driveshaft form a walking beam assembly to sequentiallydisplace the follower in a distal direction during each actuation cycleof the fastener deployment system.
 35. The surgical instrument of claim34 further comprising an anti-backup element associated with thefollower, wherein distal movement of the follower distally extends theanti-backup element.
 36. The surgical instrument of claim 34, whereinthe follower is displaced by a fastener length during each actuationcycle.
 36. A surgical instrument comprising: a handle; an elongatedshaft assembly extending distally from the handle; a fastener deploymentsystem for deploying fasteners from the elongated shaft assembly,wherein the fastener deployment system includes a driveshaft; ananti-backup element associated with the driveshaft, wherein actuation ofthe fastener deployment system distally displaces the driveshaft, andwherein distal movement of the driveshaft extends the anti-backupelement by a preselected length during each actuation cycle.
 37. Thesurgical instrument of claim 36, wherein the preselected length is afastener length.